Mobile broadband will continue to drive the demands for big overall traffic capacity and huge achievable end-user data rates in a wireless network. Several scenarios may require data rates of up to 10 Gbps in a local area. These demands for very high system capacity and very high end-user date rates can be met by networks with distances between access nodes ranging from a few meters in indoor deployments up to roughly 50 m in outdoor deployments, i.e. with an infra-structure density considerably higher than the densest networks of today. Such networks may be referred as a new radio (NR) system. Besides traditional licensed exclusive bands, the NR system is also expected to be operating on unlicensed band.
Unlicensed band refers to radio frequency bands that are open for shared use by an unlimited number of compliant users. For various wireless communication systems operated in the shared unlicensed spectrum such as 2.4 GHz and 5 GHz, carrier sensing scheme is used when accessing a channel. That is, before accessing a channel or carrier by a wireless communication system, the wireless communication system shall firstly determine the channel is available via sensing the channel. If the channel is determined as unavailable, the wireless communication system shall not access the channel. Carrier sensing may also be interchangeably referred to as listen-before-talk (LBT) hereinafter. In addition, when the wireless communication system is required to receive a particular signal such as a discovery reference signal (DRS) or random access signal, it has to keep monitoring the particular signal on at least a channel.
However, there are some changes made in the NR system compared to existing networks/systems. This results in that some solutions in existing networks/systems might not suit the NR system very well. Therefore, it would be desirable to provide a solution for transmission in the NR system.